Electrode assembly

ABSTRACT

An electrode assembly includes a cell stack part having (a) a structure in which one kind of radical unit having a same number of electrodes and separators alternately disposed and integrally combined is repeatedly disposed, or (b) a structure in which at least two kinds of radical units having a same number of electrodes and separators alternately disposed and integrally combined are disposed in a predetermined order, and a fixing part extending from a top surface along a side to a bottom surface thereof for fixing the cell stack part. The one kind of radical unit has a four-layered structure in which first electrode, first separator, second electrode and second separator are sequentially stacked or a repeating structure in which the four-layered structure is repeatedly stacked, and each of the at least two kinds of radical units are stacked by ones to form the four-layered structure or the repeating structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.10-2013-0016514 filed on Feb. 15, 2013, in the Korean IntellectualProperty Office and Application No. 10-2014-0017716 filed on Feb. 17,2014, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an electrode assembly, and moreparticularly, to an electrode assembly having good stacking stabilitythat may be realized through stacking.

BACKGROUND ART

Secondary batteries maybe classified into various types according to thestructure of an electrode assembly. Typically, secondary batteries maybe classified into a stack-type, a wrapping-type (a jelly-roll type), ora stack/folding type according to the structure of an electrodeassembly. The stack-type structure may be obtained by separatelystacking electrode units (a cathode, a separator, and an anode)constituting the electrode assembly, and thus an accurate alignment ofthe electrode assembly is very difficult. In addition, a large number ofprocesses are necessary for the manufacture of the electrode assembly.The stack/folding type structure is generally manufactured by using twolamination apparatuses and one folding apparatus, and thus themanufacture of the electrode assembly is very complicated. Particularly,in the stack/folding type structure, full cells or bi-cells are stackedthrough folding, and thus the alignment of the full cells or thebi-cells is difficult.

SUMMARY OF THE INVENTION

The applicant of the present disclosure has been filed a novel typeelectrode assembly that may be manufactured only by stacking and thatmay be accurately aligned with improved productivity. The presentdisclosure basically relates to the electrode assembly having improvedstacking stability.

An aspect of the present disclosure provides an electrode assembly thatmay be realized by stacking and has good stacking stability.

According to an aspect of the present disclosure, there is provided anelectrode assembly including a cell stack part having (a) a structure inwhich one kind of radical unit is repeatedly disposed, the one kind ofradical unit having a same number of electrodes and separators which arealternately disposed and integrally combined, or (b) a structure inwhich at least two kinds of radical units are disposed in apredetermined order, the at least two kinds of radical units each havinga same number of electrodes and separators which are alternatelydisposed and integrally combined, and a fixing part extending from a topsurface of the cell stack part along a side of the cell stack part to abottom surface of the cell stack part for fixing the cell stack part.The one kind of radical unit of (a) has a four-layered structure inwhich a first electrode, a first separator, a second electrode and asecond separator are sequentially stacked together or a repeatingstructure in which the four-layered structure is repeatedly stacked, andwherein each of the at least two kinds of radical units are stacked byones in the predetermined order to form the four-layered structure orthe repeating structure in which the four-layered structure isrepeatedly stacked.

In an electrode assembly according to the present disclosure, since acell stack part has a structure based on stacking, and a fixing partfixes the cell stack part, the electrode assembly may be easily realizedby stacking and has good stacking stability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view illustrating a first structure of a radical unitaccording to the present disclosure;

FIG. 2 is a side view illustrating a second structure of a radical unitaccording to the present disclosure;

FIG. 3 is a side view illustrating a cell stack part formed by stackingthe radical units of FIG. 1;

FIG. 4 is a side view illustrating a third structure of a radical unitaccording to the present disclosure;

FIG. 5 is a side view illustrating a fourth structure of a radical unitaccording to the present disclosure;

FIG. 6 is a side view illustrating a cell stack part formed by stackingthe radical units of FIG. 4 and the radical units of FIG. 5;

FIG. 7 is a process diagram illustrating a manufacturing process of aradical unit according to the present disclosure;

FIG. 8 is a perspective view illustrating a cell stack part formed bystacking radical units having different sizes;

FIG. 9 is a side view illustrating the cell stack part of FIG. 8;

FIG. 10 is a perspective view illustrating a cell stack part formed bystacking radical units having different geometric shapes;

FIG. 11 is a side view illustrating a first structure of a cell stackpart including a radical unit and a first auxiliary unit according tothe present disclosure;

FIG. 12 is a side view illustrating a second structure of a cell stackpart including a radical unit and a first auxiliary unit according tothe present disclosure;

FIG. 13 is a side view illustrating a third structure of a cell stackpart including a radical unit and a second auxiliary unit according tothe present disclosure;

FIG. 14 is a side view illustrating a fourth structure of a cell stackpart including a radical unit and a second auxiliary unit according tothe present disclosure;

FIG. 15 is a side view illustrating a fifth structure of a cell stackpart including a radical unit and a first auxiliary unit according tothe present disclosure;

FIG. 16 is a side view illustrating a sixth structure of a cell stackpart including a radical unit and a first auxiliary unit according tothe present disclosure;

FIG. 17 is a side view illustrating a seventh structure of a cell stackpart including a radical unit and a second auxiliary unit according tothe present disclosure;

FIG. 18 is a side view illustrating an eighth structure of a cell stackpart including a radical unit and a second auxiliary unit according tothe present disclosure;

FIG. 19 is a side view illustrating a ninth structure of a cell stackpart including a radical unit and a first auxiliary unit according tothe present disclosure;

FIG. 20 is a side view illustrating a tenth structure of a cell stackpart including a radical unit, a first auxiliary unit, and a secondauxiliary unit according to the present disclosure;

FIG. 21 is a side view illustrating an eleventh structure of a cellstack part including a radical unit and a second auxiliary unitaccording to the present disclosure;

FIG. 22 is a perspective view illustrating an electrode assemblyincluding a fixing part according to an embodiment of the presentdisclosure;

FIG. 23 is a plan view illustrating the electrode assembly in FIG. 22;

FIGS. 24 and 25 are plan views illustrating first and secondmodification embodiments of the fixing part in FIG. 23;

FIG. 26 is a plan view illustrating a third modification embodiment ofthe fixing part in FIG. 23;

FIG. 27 is a plan view illustrating a fourth modification embodiment ofthe fixing part in FIG. 23;

FIG. 28 is a plan view illustrating a fifth modification embodiment ofthe fixing part in FIG. 23;

FIGS. 29 and 30 are plan views illustrating sixth and seventhmodification embodiments of the fixing part in FIG. 23;

FIG. 31 is a plan view illustrating an eighth modification embodiment ofthe fixing part in FIG. 23;

FIG. 32 is a perspective view illustrating the electrode assembly inFIG. 31; and

FIGS. 33 and 34 are plan views illustrating first and secondmodification embodiments of the fixing part in FIG. 31.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present disclosure will now be described indetail with reference to the accompanying drawings. However, the presentdisclosure is not restricted or limited to the following exemplaryembodiments.

The electrode assembly according to the present disclosure basicallyincludes a cell stack part and a fixing part for fixing the cell stackpart. Hereinafter, the cell stack part will be explained first and then,the fixing part will be explained.

Cell Stack Part

The cell stack part has a structure obtained by repeatedly disposing onekind of radical units or a structure obtained by disposing at least twokinds of radical units in a predetermined order, for example,alternately. This will be described below in more detail.

[Structure of Radical Unit]

In an electrode assembly according to the present disclosure, a radicalunit is formed by alternately disposing electrodes and separators. Here,the same number of electrodes and separators are disposed. For example,as illustrated in FIG. 1 a radical unit 110 a may be formed by stackingtwo electrodes 111 and 113 and two separators 112 and 114. Here, acathode and an anode may naturally face each other through theseparator. When the radical unit is formed as described above, anelectrode 111 is positioned at one end of the radical unit (see theelectrode 111 in FIGS. 1 and 2) and a separator 114 is positioned at theother end of the radical unit (see the separator 114 in FIGS. 1 and 2).

The electrode assembly according to the present disclosure is basicallycharacterized in that the cell stack part or electrode assembly isformed by only stacking the radical units. That is, the presentdisclosure has a basic characteristic in that the cell stack part isformed by repeatedly stacking one kind of radical unit or by stacking atleast two kinds of radical units in a predetermined order. To realizethe above-described characteristic, the radical unit may have thefollowing structure.

First, the radical unit may be formed by stacking a first electrode, afirst separator, a second electrode, and a second separator in sequence.In more detail, a first electrode 111, a first separator 112, a secondelectrode 113, and a second separator 114 may be stacked in sequencefrom an upper side to a lower side, as illustrated in FIG. 1, or fromthe lower side to the upper side, as illustrated in FIG. 2, to formradical units 110 a and 110 b. The radical unit having theabove-described structure maybe referred to as a first radical unit.Here, the first electrode 111 and the second electrode 113 may beopposite types of electrodes. For example, when the first electrode 111is a cathode, the second electrode 113 may be an anode.

As described above, the radical unit may be formed by stacking the firstelectrode 111, the first separator 112, the second electrode 113, andthe second separator 114 in sequence. Then, a cell stack part 100 a maybe formed by only repeatedly stacking the one kind of radical units 110a as illustrated in FIG. 3. Here, the radical unit may have aneight-layered structure or twelve-layered structure in addition to afour-layered structure. That is, the radical unit may have a repeatingstructure in which the four-layered structure is repeatedly disposed.For example, the radical unit may be formed by stacking the firstelectrode 111, the first separator 112, the second electrode 113, thesecond separator 114, the first electrode 111, the first separator 112,the second electrode 113, and the second separator 114 in sequence.

Alternatively, the radical unit may be formed by stacking the firstelectrode 111, the first separator 112, the second electrode 113, thesecond separator 114, the first electrode 111, and the first separator112 in sequence, or by stacking the second electrode 113, the secondseparator 114, the first electrode 111, the first separator 112, thesecond electrode 113, and the second separator 114 in sequence. Theradical unit having the former structure may be referred to as a secondradical unit and the radical unit having the latter structure may bereferred to as a third radical unit.

In more detail, the second radical unit 100 c may be formed by stackingthe first electrode 111, the first separator 112, the second electrode113, the second separator 114, the first electrode 111, and the firstseparator 112 in sequence from the upper side to the lower side, asillustrated in FIG. 4. Also, the third radical structure 110 d may beformed by stacking the second electrode 113, the second separator 114,the first electrode 111, the first separator 112, the second electrode113, and the second separator 114 in sequence from the upper side to thelower side, as illustrated in FIG. 5. As noted above, the stacking maybe conducted in sequence from the lower side to the upper side.

When only one of the second radical units 110 c and one of the thirdradical units 110 d are stacked, a repeating structure in which thefour-layered structure is repeatedly stacked may be formed. Thus, whenthe second radical unit 110 c and the third radical unit 110 d arealternately stacked one by one, the cell stack part 100 b may be formedby stacking only the second and third radical units, as illustrated inFIG. 6. For reference, when three kinds of radical units are prepared,the cell stack part may be formed by stacking the radical units in apredetermined order, for example, the first radical unit, the secondradical unit, the third radical unit, the first radical unit again, thesecond radical unit, and the third radical unit.

As described above, the one kind of radical unit in the presentdisclosure has a four-layered structure in which a first electrode, afirst separator, a second electrode and a second separator aresequentially stacked, or has a repeating structure in which thefour-layered structure is repeatedly stacked. Also, at least two kindsof radical units in the present disclosure are stacked only by ones in apredetermined order to form the four-layered structure or the repeatingstructure in which the four-layered structure is repeatedly disposed.For example, the first radical unit forms a four-layered structure byitself, and the second radical unit and the third radical unit form atwelve-layered structure by stacking one of each, that is, two radicalunits in total.

Thus, the cell stack part or electrode assembly may be formed only bystacking, that is, by repeatedly stacking one kind of radical unit or bystacking at least two kinds of radical units in a predetermined order.

The cell stack part of the present disclosure may be formed by stackingthe radical units one by one. That is, the cell stack part may bemanufactured by forming the radical units and then stacking the radicalunits repeatedly or in a predetermined order. As described above, thecell stack part of the present disclosure may be formed by only stackingthe radical units. Therefore, the radical units of the presentdisclosure may be very accurately aligned. When the radical unit isaccurately aligned, the electrode and the separator may also beaccurately aligned in the cell stack part. In addition, the cell stackpart or electrode assembly may be improved in productivity. This is donebecause the manufacturing process is very simple.

[Manufacture of Radical Unit]

A manufacturing process of the first radical unit will be exemplarilydescribed with reference to FIG. 7. First, a first electrode material121, a first separator material 122, a second electrode material 123 anda second separator material 124 are prepared. Here, the first separatormaterial 122 and the second separator material 124 may be the same. Thefirst electrode material 121 is cut into a certain size through a cutterC1, and the second electrode material 123 is cut into a certain sizethrough a cutter C2. Then, the first electrode material 121 is stackedon the first separator material 122, and the second electrode material123 is stacked on the second separator material 124.

Then, it is preferable that the electrode materials and the separatormaterials are attached to each other through laminators L1 and L2.Through the attachment, a radical unit in which the electrodes and theseparators are integrally combined may be formed. The combining methodmay be diverse. The laminators L1 and L2 may apply pressure to thematerials or apply pressure and heat to the materials to attach thematerials to each other. Because of the attachment, the stacking of theradical units may be more easily performed while manufacturing the cellstack part. Also, the alignment of the radical units may be also easilyaccomplished because of the attachment. After the attachment, the firstseparator material 122 and the second separator material 124 are cutinto a certain size through a cutter C3 to manufacture the radical unit110 a. During this process, the edges of the separators are not joinedwith each other.

As described above, the electrode may be attached to the adjacentseparator in the radical unit. Alternatively, the separator may beattached to the adjacent electrode. Here, it is preferable that anentire surface of the electrode facing the adjacent separator isattached to the adjacent separator. In this case, the electrode may bestably fixed to the separator. Typically, the electrode has a size lessthan that of the separator.

For this, an adhesive may be applied to the separator. However, when theadhesive is used, it is necessary to apply the adhesive over an adhesionsurface of the separator in a mesh or dot shape. This is because if theadhesive is closely applied to the entire adhesion surface, reactiveions such as lithium ions may not pass through the separator. Thus, whenthe adhesive is used, it is difficult to allow the overall surface ofthe electrode to closely attach to the adjacent separator.

Alternatively, use of the separator including the coating layer havingadhesive strength makes it possible to generally attach the electrode tothe separator. This will be described below in more detail. Theseparator may include a porous separator base material such as apolyolefin-based separator base material and a porous coating layer thatis generally applied to one side or both sides of the separator basematerial. Here, the coating layer may be formed of a mixture ofinorganic particles and a binder polymer that binds and fixes theinorganic particles to each other.

Here, the inorganic particles may improve thermal stability of theseparator. That is, the inorganic particles may prevent the separatorfrom being contracted at a high temperature. In addition, the binderpolymer may fix the inorganic particles to improve mechanical stabilityof the separator. Also, the binder polymer may attach the electrode tothe separator. Since the binder polymer is generally distributed in thecoating layer, the electrode may closely adhere to the entire adhesionsurface of the separator, unlike the foregoing adhesive. Thus, when theseparator is used as described above, the electrode may be more stablyfixed to the separator. To enhance the adhesion, the above-describedlaminators may be used.

The inorganic particles may have a densely packed structure to forminterstitial volumes between the inorganic particles over the overallcoating layer. Here, a pore structure may be formed in the coating layerby the interstitial volumes that are defined by the inorganic particles.Due to the pore structure, even though the coating layer is formed onthe separator, the lithium ions may smoothly pass through the separator.For reference, the interstitial volume defined by the inorganicparticles may be blocked by the binder polymer according to a positionthereof.

Here, the densely packed structure may be explained as a structure inwhich gravels are contained in a glass bottle. Thus, when the inorganicparticles form the densely packed structure, the interstitial volumesbetween the inorganic particles are not locally formed in the coatinglayer, but generally formed in the coating layer. As a result, when eachof the inorganic particles increases in size, the pore formed by theinterstitial volume also increases in size. Due the above-describeddensely packed structure, the lithium ions may smoothly pass through theseparator over the entire surface of the separator.

The radical units may also adhere to each other in the cell stack part.For example, if the adhesive or the above-described coating layer isapplied to a bottom surface of the second separator 114 in FIG. 1, theother radical unit may adhere to the bottom surface of the secondseparator 114.

Here, the adhesive strength between the electrode and the separator inthe radical unit may be greater than that between the radical units inthe cell stack part. It is understood, that the adhesive strengthbetween the radical units may not be provided. In this case, when theelectrode assembly or the cell stack part is disassembled, the electrodeassembly may be separated into the radical units due to a difference inthe adhesive strength. For reference, the adhesive strength maybeexpressed as delamination strength. For example, the adhesive strengthbetween the electrode and the separator may be expressed as a forcerequired for separating the electrode from the separator. In thismanner, the radical unit may not be bonded to the adjacent radical unitin the cell stack part, or may be bonded to the adjacent radical unit inthe cell stack part by means of a bonding strength differing from abonding strength between the electrode and the separator.

For reference, when the separator includes the above-described coatinglayer, it is not preferable to perform ultrasonic welding on theseparator. Typically, the separator has a size greater than that of theelectrode. Thus, there may be an attempt to bond the edge of the firstseparator 112 to the edge of the second separator 114 through theultrasonic welding. Here, it is necessary to directly press an object tobe welded through a horn in the ultrasonic welding. However, when theedge of the separator is directly pressed through the horn, theseparator may adhere to the horn due to the coating layer having theadhesive strength. As a result, the welding apparatus may be brokendown.

[Modification of Radical Unit]

Until now, the radical units having the same size have been explained.However, the radical units may have different sizes. When stacking theradical units having different sizes, cell stack parts having variousshapes may be manufactured. Herein, the size of the radical unit isexplained with reference to the size of the separator, because,typically, the separator is larger than the electrode.

Referring to FIGS. 8 and 9, a plurality of radical units is prepared andmay be classified into at least two groups having different sizes (seereference numerals 1101 a, 1102 a and 1103 a in FIG. 9). By stacking theradical units according to their sizes, a cell stack part 100 c having astructure of a plurality of steps may be formed. FIGS. 8 and 9illustrate an embodiment in which the cell stack part includes threesteps obtained by stacking the radical units 1101 a, 1102 a and 1103 aclassified into three groups, in which the radical units having the samesize are stacked together, is illustrated. Therefore, the cell stackpart 100 c in FIGS. 8 and 9 has a structure including three steps. Forreference, the radical units included in one group may form two or moresteps.

When the plurality of steps is formed as described above, it ispreferable that the radical unit has a structure of the first radicalunit, that is, the above-described four-layered structure or therepeating structure in which the four-layered structure is repeatedlystacked. (Herein, the radical units are considered to be included in onekind of radical unit even though the radical units have the same stackedstructures but have different sizes.)

Preferably, the same number of cathodes and the anodes are stacked inone step. Also, it is preferable that opposite electrodes face eachother through a separator between one step and another step. Forexample, in case of the second and third radical units, two kinds of theradical units are necessary for forming one step.

However, in case of the first radical unit, only one kind of radicalunit is necessary for forming one step as illustrated in FIG. 9. Thus,when the radical unit has the four-layered structure or the repeatingstructure in which the four-layered structure is repeatedly stacked,number of kinds of radical units may decrease even though a plurality ofthe steps is formed.

Also, in case of the second and the third radical units, at least one ofthe two kinds of the radical units are necessary to be stacked to formone step. Thus, the one step may have at least a twelve-layeredstructure. However, in case of the first radical unit, only one kind ofradical unit is necessary to be stacked to form one step. Thus, one stepmay have at least a four-layered structure. As a result, when theradical unit has the four-layered structure or the repeating structurein which the four-layered structure is repeatedly stacked, the thicknessof each step may be easily controlled when forming a plurality of steps.

The radical units may have not only different sizes but also differentgeometric shapes. For example, the radical units may have differentsizes and different edge shapes, and may or may not have a through holeas illustrated in FIG. 10. More particularly, as illustrated in FIG. 10,a plurality of radical units classified into three groups may form threesteps by stacking the radical units having the same geometric shapes.

For this, the radical units may be classified into at least two groups(each of the groups has different geometric shape). Similarly, theradical unit may preferably have the four-layered structure or therepeating structure in which the four-layered structures are repeatedlystacked, that is, the structure of the first radical unit. (Herein, theradical units are considered to be included in one kind of radical uniteven though the radical units have the same stacked structure but havedifferent geometric shapes.)

[Auxiliary Unit]

The cell stack part may further include at least one of a firstauxiliary unit and/or a second auxiliary unit. First, the firstauxiliary unit will be described below. In the present disclosure, anelectrode is positioned at one end of the radical unit, and a separatoris positioned at the other end of the radical unit. When the radicalunits are stacked in sequence, the electrode may be positioned at theuppermost portion or at the lowermost portion of the cell stack part(see reference numeral 116 in FIG. 11, and this electrode may bereferred to as a terminal electrode 116). The first auxiliary unit isadditionally stacked on the terminal electrode.

In more detail, when the terminal electrode 116 is a cathode, the firstauxiliary unit 130 a may be formed by stacking outward from the terminalelectrode 116, a separator 114, an anode 113, a separator 112, and acathode 111 in sequence, as illustrated in FIG. 11. On the other hand,when the terminal electrode 116 is an anode, the first auxiliary unit130 b may be formed by stacking outward from the terminal electrode 116,the separator 114, and the cathode 113 in sequence, as illustrated inFIG. 12.

In the cell stack parts 100 d and 100 e, a cathode may be positioned atthe outermost portion through the first auxiliary units 130 a and 130 b,as illustrated in FIGS. 11 and 12. In this case, in the cathodepositioned at the outermost portion, that is, the cathode of the firstauxiliary unit, an active material layer is preferably coated on onlyone side facing the radical unit (one side facing downward in FIG. 11)among both sides of the current collector. When the one side of thecurrent collector is coated with the active material layer as describedabove, the active material layer is not positioned at the outermostportion of the cell stack part. Thus, waste of the active material layermay be prevented. For reference, since the cathode emits, for example,lithium ions, when the cathode is positioned at the outermost portion,the capacity of a battery may be improved.

Next, a second auxiliary unit will be described below. The secondauxiliary unit performs the same function as the first auxiliary unit,which will be described below in more detail. In the present disclosure,an electrode is positioned at one end of the radical unit, and aseparator is positioned at the other end of the radical unit. When theradical units are stacked in sequence, the separator may be positionedat the uppermost portion or at the lowermost portion of the cell stackpart (see reference numeral 117 in FIG. 13, and this separator may bereferred to as a terminal separator 117). The second auxiliary unit isadditionally stacked on the terminal separator.

In more detail, when the electrode 113 contacting the terminal separator117 is a cathode in the radical unit, the second auxiliary unit 140 amay be formed by stacking from the terminal separator 117, an anode 111,a separator 112, and a cathode 113 in sequence, as illustrated in FIG.13. On the other hand, when the electrode 113 contacting the terminalseparator 117 is an anode in the radical unit, the second auxiliary unit140 b may be formed as the cathode 111, as illustrated in FIG. 14.

In the cell stack parts 100 f and 100 g, a cathode may be positioned atthe outermost portion of the terminal separator through the secondauxiliary units 140 a and 140 b, as illustrated in FIGS. 13 and 14. Inthis case, in the cathode positioned at the outermost portion, that is,the cathode of the second auxiliary unit, an active material layer ispreferably coated on only one side facing the radical unit (one sidefacing upward in FIG. 13) among both sides of the current collector, assimilar to the cathode of the first auxiliary unit.

The first auxiliary unit and the second auxiliary unit may havedifferent structures from those described above. First, the firstauxiliary unit will be described below. When the terminal electrode 116is a cathode as illustrated in FIG. 15, the first auxiliary unit 130 cmay be formed by stacking from the terminal electrode 116, a separator114, and an anode 113 in sequence. On the other hand, when the terminalelectrode 116 is an anode as illustrated in FIG. 16, the first auxiliaryunit 130 d may be formed by stacking from the terminal electrode 116, aseparator 114, a cathode 113, a separator 112, and an anode 111 insequence.

In the cell stack parts 100 h and 100 i, the anode may be positioned atthe outermost portion of the terminal electrode through the firstauxiliary units 130 c and 130 d as illustrated in FIGS. 15 and 16.

Next, the second auxiliary unit will be described below. As illustratedin FIG. 17, when the electrode 113 contacting the terminal separator 117is a cathode in the radical unit, the second auxiliary unit 140 c may beformed as an anode 111. As illustrated in FIG. 18, when the electrode113 contacting the terminal separator 117 is an anode in the radicalunit, the second auxiliary unit 140 d may be formed by stacking from theterminal separator 117, the cathode 111, the separator 112, and theanode 113 in sequence. In the cell stack parts 100 j and 100 k, an anodemay be positioned at the outermost portion of the terminal separatorthrough the second auxiliary units 140 c and 140 d as illustrated inFIGS. 17 and 18.

For reference, an anode may make a reaction with an aluminum layer of abattery case (for example, a pouch-type case) due to potentialdifference. Thus, the anode is preferably insulated from the batterycase by means of a separator. For this, the first and second auxiliaryunits in FIGS. 15 to 18 may further include a separator at the outerportion of the anode. For example, the first auxiliary unit 130 e inFIG. 19 may further include a separator 112 at the outermost portionthereof when compared with the first auxiliary unit 130 c in FIG. 15.For reference, when the auxiliary unit includes the separator, thealignment of the auxiliary units in the radical unit may be easilyperformed.

A cell stack part 100 m may be formed as illustrated in FIG. 20. Aradical unit 110 b may be formed by stacking from the lower portion tothe upper portion, a first electrode 111, a first separator 112, asecond electrode 113, and a second separator 114 in sequence. In thiscase, the first electrode 111 may be a cathode, and the second electrode113 may be an anode.

A first auxiliary unit 130 f may be formed by stacking from the terminalelectrode 116, the separator 114, the anode 113, the separator 112 andthe cathode 111 in sequence. In this case, in the cathode 111 of thefirst auxiliary unit 130 f, only one side of a current collector facingthe radical unit 110 b among both sides of the current collector may becoated with an active material layer.

Also, a second auxiliary unit 140 e may be formed by stacking from theterminal separator 117, the cathode 111 (the first cathode), theseparator 112, the anode 113, the separator 114, and the cathode 118(the second cathode) in sequence. In this case, in the cathode 118 (thesecond cathode) of the second auxiliary unit 140 e positioned at theoutermost portion, only one side of a current collector facing theradical unit 110 b among both sides of the current collector may becoated with an active material layer.

Finally, a cell stack part 100 n may be formed as illustrated in FIG.21. A radical unit 110 e may be formed by stacking from the upperportion to the lower portion, a first electrode 111, a first separator112, a second electrode 113, and a second separator 114 in sequence. Inthis case, the first electrode 111 may be an anode, and the secondelectrode 113 may be a cathode. Also, a second auxiliary unit 140 fmaybe formed by stacking from the terminal separator 117, the anode 111,the separator 112, the cathode 113, the separator 114, and the anode 119in sequence.

Fixing Part

The electrode assembly of the present disclosure includes a fixing partfor fixing the cell stack part. The electrode assembly according to thepresent disclosure has basic properties in forming the cell stack part(electrode assembly) by only stacking the radical units. However, whenthe cell stack part is formed by stacking the radical units, gaps may begenerated between the radical units. The gaps may also be generatedbetween an electrode and a separator. Due to the generation of the gaps,the electrode assembly may be disassembled. Thus, to secure the stackingstability of the electrode assembly, the prevention of the generation ofthe gaps is necessary. For this, the electrode assembly of the presentdisclosure includes a fixing part.

As illustrated in FIG. 22, a fixing part 200 is extended from the topsurface of the cell stack part 100 along the side of the cell stack part100 to the bottom surface of the cell stack part 100 and fixes the cellstack part 100. Even though the cell stack part includes a plurality ofsteps as illustrated in FIG. 8, the cell stack part may also be fixed bymeans of the fixing part. For reference, a cell stack part including oneradical unit is illustrated in FIG. 22.

Here, the fixing part 200 preferably fixes the cell stack part 100 bypressing the cell stack part 100 inwardly.

Particularly, the cell stack part 100 may be fixed by the following. Oneend of a polymer tape is fixed to the top surface of the cell stack part100 by heat welding, and the other end of the polymer tape is drawnalong the side of the cell stack part 100 and is heat welded to thebottom surface of the cell stack part 100. Through the procedure, thecell stack part 100 may be fixed by the fixing part 200 more stably.

Meanwhile, electrode terminals or electrode tabs 310 and 320 makingelectrical connections with electrodes of the cell stack part 100 may beextended in opposite directions from each other according to thepolarity as illustrated in FIG. 22. For example, a cathode terminal maybe extended frontward, and an anode terminal may be extended rearward.Alternatively, the electrode terminals may be extended in the samedirection with a distance between them according to the polarity.

The fixing part 200 may be formed by the process described above (seeFIGS. 22 and 23). In this case, two fixing parts 200 in parallel to afirst direction D1, which will be explained later, may be provided atthe sides of the cell stack part 100 among four sides of the cell stackpart 100 as illustrated in FIG. 23.

Here, fixing parts 201 and 202 may be provided in plural along the firstdirection D1 (see FIG. 23) as illustrated in FIG. 24 or 25. (Two fixingparts are provided at the left side along the first direction, and twofixing parts are provided at the right side along the first direction inFIG. 24.) By forming the fixing parts 201 and 202, the generation ofgaps at the outer portion of the cell stack part 100 may be effectivelyprevented. In addition, when a fixing part 203 is formed as illustratedin FIG. 26, the generation of the gaps at the outer portion of the cellstack part 100 may be more effectively prevented.

The first direction D1 may be defined on a plane obtained by projectingthe cell stack part 100 in a height direction (up and down in FIG. 22).As illustrated in FIG. 22, the cell stack part 100 in this embodimenthas a rectangular shape. (Generally, a separator is the biggest, and theseparator will be explained as a reference.) When the cell stack part100 is projected in the height direction, a rectangle is obtained (seeFIG. 23). The rectangle has four sides. Two of them are extended in thefirst direction D1 and are in parallel to each other, and the remainingtwo of them are extended in a second direction D2 which is perpendicularto the first direction D1 and are in parallel to each other. The firstdirection D1 and the second direction D2 may be defined as describedabove. However, the plane obtained by projecting the cell stack part isnot necessary to be a rectangle.

Meanwhile, the fixing part 200 in FIG. 23 may be modified as that inFIG. 27. That is, two fixing parts 204 may be provided at the two sidesin parallel to the second direction D2 (see FIG. 23) in the cell stackpart 100 as illustrated in FIG. 27. Here, a plurality of the fixingparts 204 may be provided along the second direction D2. (Two fixingparts are provided at the upper part along the second direction, and twofixing parts are provided at the bottom part along the second directionin FIG. 27.)

As illustrated in FIG. 28, fixing parts 205 may be provided at foursides of the cell stack part 100. For reference, the first direction D1and the second direction D2 are relative. For example, the upper sideand the bottom side of the cell stack part in FIG. 28 may be defined asa direction in parallel to the first direction D1.

In addition, the thickness of fixing parts 206 and 207 may be changed asillustrated in FIGS. 29 and 30 from that of the fixing part 200 in FIG.23. When the thickness of the fixing parts 206 and 207 is increased asillustrated in FIGS. 29 and 30, the cell stack part 100 may be fixedmore stably. For reference, the fixing parts 207 are provided at allsides of the cell stack part 100 in FIG. 30.

Meanwhile, the cell stack part 100 may be wrapped in a fixing part 208by at least one lap in a direction in parallel to the second directionD2 as illustrated in FIGS. 31 and 32. That is, after extending thefixing part 208 from the top surface of the cell stack part 100 alongthe side of the cell stack part 100 to the bottom surface of the cellstack part 100, the fixing part 208 may be extended from the bottomsurface of the cell stack part 100 along the other side of the cellstack part 100 to the top surface of the cell stack part 100. By formingthe fixing part 208 as described above, the cell stack part 100 may befixed more stably when compared to the fixing using the fixing part 200as in FIG. 23.

For reference, the length of the fixing part 200 in FIG. 23 is shorterwhen compared to that of the fixing part 208 in FIG. 31. Thus, the unitprice of an electrode assembly may decrease when using the fixing part200 in FIG. 23. In addition, the thickness of an electrode assembly maydecrease when the fixing part 200 in FIG. 23 is formed when compared tothe fixing part 208 in FIG. 31. In the fixing part 200 in FIG. 23, thefixing part 200 is not formed at the center portion of the top surfaceand the bottom surface of the cell stack part 100. However, in thefixing part 208 in FIG. 31, the fixing part 208 is formed at the centerportion of the top surface and the bottom surface of the cell stack part100.

The fixing part 208 in FIG. 31 may be modified as in FIG. 33 or 34. Thatis, a plurality of fixing parts 209 maybe provided in the firstdirection D1 as illustrated in FIG. 33. Alternatively, the fixing part210 may wrap the cell stack part 100 by one lap or more than two laps ina direction in parallel to the first direction D1 as illustrated in FIG.34. In this case, a plurality of the fixing parts 210 may be provided inthe second direction D2.

This application claims the priority of Korean Patent Application No.10-2013-0016514 filed on Feb. 15, 2013, and Application No.10-2014-0017716 filed on Feb. 17, 2014 in the Korean IntellectualProperty Office, the disclosures of which are expressly incorporatedherein by reference in their entireties.

1. An electrode assembly, comprising: a cell stack part having (a) astructure in which one kind of radical unit is repeatedly disposed, theone kind of radical unit having a same number of electrodes andseparators which are alternately disposed and integrally combined, or(b) a structure in which at least two kinds of radical units aredisposed in a predetermined order, the at least two kinds of radicalunits each having a same number of electrodes and separators which arealternately disposed and integrally combined; and a fixing partextending from a top surface of the cell stack part along a side of thecell stack part to a bottom surface of the cell stack part for fixingthe cell stack part, wherein the one kind of radical unit of (a) has afour-layered structure in which a first electrode, a first separator, asecond electrode and a second separator are sequentially stackedtogether or a repeating structure in which the four-layered structure isrepeatedly stacked; and wherein each of the at least two kinds ofradical units of (b) are stacked by ones in the predetermined order toform the four-layered structure or the repeating structure in which thefour-layered structure is repeatedly stacked.
 2. The electrode assemblyof claim 1, wherein edges of adjacent separators are not joined witheach other.
 3. The electrode assembly of claim 1, wherein adjacentradical units are not combined with each other in the cell stack part,or are combined with each other in the cell stack part with a combiningstrength differing from a combining strength between the electrode andthe separator in the radical unit.
 4. The electrode assembly of claim 1,wherein, when a plane defined by a projection of the cell stack part ina height direction has two parallel sides extending in a first directionand two parallel sides extending in a second direction substantiallyperpendicular to the first direction, the fixing part is provided ateach of two sides of the cell stack part that are parallel to the firstdirection among sides of the cell stack part.
 5. The electrode assemblyof claim 4, wherein a plurality of the fixing parts is provided at eachof the two sides that are parallel to the first direction.
 6. Theelectrode assembly of claim 4, wherein the fixing part is also providedat each of two other sides of the cell stack part that are parallel tothe second direction among the sides of the cell stack part.
 7. Theelectrode assembly of claim 6, wherein a plurality of the fixing partsis provided at each of the two sides that are parallel to the seconddirection.
 8. The electrode assembly of claim 1, wherein, when a planedefined by a projection of the cell stack part in a height direction hastwo parallel sides extending in a first direction and two parallel sidesextending in a second direction substantially perpendicular to the firstdirection, the fixing part wraps the cell stack part by at least one lapin a direction parallel to the first direction.
 9. The electrodeassembly of claim 8, wherein the fixing parts are provided in pluralityand the fixing parts are separated in the second direction from eachother.
 10. The electrode assembly of claim 1, wherein the fixing partfixes the cell stack part by pressing the cell stack part inwardly. 11.The electrode assembly of claim 1, wherein the fixing part comprises apolymer tape.
 12. The electrode assembly of claim 1, wherein the onekind of radical unit of (a) comprises a first radical unit having thefour-layered structure or the repeating structure in which thefour-layered structure is repeatedly stacked, and wherein the cell stackpart has a structure in which the first radical units are repeatedlydisposed.
 13. The electrode assembly of claim 1, wherein the at leasttwo kinds of radical units of (b) comprises: a second radical unithaving the first electrode, the first separator, the second electrode,the second separator, the first electrode, and the first separator,which are sequentially disposed and integrally combined; and a thirdradical unit having the second electrode, the second separator, thefirst electrode, the first separator, the second electrode, and thesecond separator, which are sequentially disposed and integrallycombined, and wherein the cell stack part has a structure in which thesecond radical unit and the third radical unit are alternately disposed.14. The electrode assembly of claim 1, wherein the one kind of radicalunit of (a) is provided in plurality and the plurality of one kind ofradical units is classified into at least two groups having differentsizes, and wherein the cell stack part has a structure in which aplurality of steps is formed by stacking the one kind of radical unitsof (a) according to the size thereof.
 15. The electrode assembly ofclaim 1, wherein the one kind of radical unit of (a) is provided inplurality and the plurality of the one kind of radical units isclassified into at least two groups having different geometric shapes,and wherein the cell stack part has a structure in which a plurality ofsteps is formed by stacking the one kind of radical units of (a)according to the geometric shape thereof.
 16. The electrode assembly ofclaim 1, wherein the electrode is attached to an adjacent separator ineach radical unit.
 17. The electrode assembly of claim 1, wherein thecell stack part further comprises a first auxiliary unit stacked on aterminal electrode that is an uppermost or a lowermost electrode,wherein, when the terminal electrode is a cathode, the first auxiliaryunit is formed by stacking from the terminal electrode, a separator, ananode, a separator, and a cathode in sequence, and wherein, when theterminal electrode is an anode, the first auxiliary unit is formed bystacking from the terminal electrode, a separator and a cathode insequence.
 18. The electrode assembly of claim 1, wherein the cell stackpart further comprises a second auxiliary unit on a terminal separatorthat is an uppermost or a lowermost separator, wherein, when theelectrode contacting the terminal separator is a cathode in the radicalunit, the second auxiliary unit is formed by stacking from the terminalseparator, an anode, a separator and a cathode in sequence, and wherein,when the electrode contacting the terminal separator is an anode in theradical unit, the second auxiliary unit is formed as a cathode.
 19. Theelectrode assembly of claim 1, wherein the cell stack part furthercomprises a first auxiliary unit stacked on a terminal electrodedisposed on an uppermost or a lowermost electrode, wherein, when theterminal electrode is a cathode, the first auxiliary unit is formed bystacking from the terminal electrode, a separator and an anode insequence, and wherein, when the terminal electrode is an anode, thefirst auxiliary unit is formed by stacking from the terminal electrode,a separator, a cathode, a separator and an anode in sequence.
 20. Theelectrode assembly of claim 1, wherein the cell stack part furthercomprises a second auxiliary unit on a terminal separator that is anuppermost or a lowermost separator, wherein, when the electrodecontacting the terminal separator is a cathode in the radical unit, thesecond auxiliary unit is formed as an anode, and wherein, when theelectrode contacting the terminal separator is an anode in the radicalunit, the second auxiliary unit is formed by stacking from the terminalseparator, a cathode, a separator, and an anode in sequence.